DTIC ADA465301: Methodology of Accelerated Life-Time Tests For Stirling-Type Bae-Co-Made Cryocoolers Against Displacer-Blockage by Cryo-Pollutant Deposits

35 Pages·1 MB·English

by  Defense Technical Information Center

REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,
gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson
Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.
1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

8 February 2000 Final Report

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Methodology Of Accelerated Life-Time Tests For Stirling-Type “Bae-Co”-Made Cryocoolers Against F61775-99-WE096
Displacer-Blockage By Cryo-Pollutant Deposits

6. AUTHOR(S)

Professor Vladimir Getmanits

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
REPORT NUMBER
R&D Bureau of the Institute for Low Temperature Physics and Engineering
ILTP&E 47 Lenin Ave N/A
Kharkov 310164
Ukraine

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
EOARD
PSC 802 BOX 14 SPC 99-4096
FPO 09499-0200

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Approved for public release; distribution is unlimited. A

13. ABSTRACT (Maximum 200 words)

This report results from a contract tasking R&D Bureau of the Institute for Low Temperature Physics and Engineering as follows: The
contractor will investigate techniques for accelerated testing of cryocooler technology. During this phase of the effort, the contractor will
perform a detailed design of the equipment needed to conduct accelerated testing. Details are contained in the proposal statement of work
designated as Tasks II and IIA.

14. SUBJECT TERMS 15. NUMBER OF PAGES

35
EOARD, Space Technology, Thermodynamics 16. PRICE CODE
N/A

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19, SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT
OF REPORT OF THIS PAGE OF ABSTRACT

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL
NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)
Prescribed by ANSI Std. 239-18
298-102
1
SPECIAL RESEARCH AND DEVELOPMENT BUREAU
IN CRYOGENIC TECHNOLOGIES OF B. VERKIN INSTITUTE
FOR LOW TEMPERATURE PHYSICS AND ENGINEERING
OF NATIONAL ACADEMY OF SCIENCES OF UKRAINE

METHODOLOGY OF ACCELERATED LIFE- TIME TESTS FOR STIRLING-
TYPE “BAE-Co”-MADE CRYOCOOLERS AGAINST DISPLACER- BLOCKAGE
BY CRYO- POLLUTANT DEPOSITS
STAND MOCK-UP EXPERIMENTS

(Interim report-Deliverable 3)

Additional Agreement
of Nov.11, 99 to #7 Contract

V.F. Getmanetz,
Program Manager

Yu.A.Pokhyl,
Business Manager

A. Ya. Levin,
V.E.Popov,
A.I.Tserkovny,
Associate Staff

January, 2000
2
Contents

pp
.
Introduction .
1. Accelerated tests methodology for Stirling- type cryocoolers against cryo-deposit
failures
2. Initial data for identification of appropriate US-made complete set equipment for
Helium Complex Stand (HCS)
3. Results of model experiments gained at stand mock-ups
3.1 Stand mock-up experiments for accelerated tests of compressor body gas
tightness under thermo- cycling
3.2 Computed estimations for different methods of cryoagent cooling for
thermocycling stand facility
3.3 Experiments for high- frequency fatigue tests mock-up of pilot prototypes of
compressor linear drive piston mount flexible springs
4. Initial data for identification of appropriate US-made complete set equipment for
compressor body thermocycling stand

5. Compressor linear drive high frequency accelerated fatigue test stand (initial data
for identification of appropriate US-made complete set equipment)
3

INTRODUCTION

Accordingly with Additional Agreement of Nov.1, 1999 to #7 Contract with “Orbita Ltd”
Co.,the SR&DB- CT-ILTPH&E- NASU executes its work activities in creation of technical
documentation to stand equipment and facilities for accelerated tests of compressors in long- life
Stirling- type linear drive cryocoolers (manufactured by “Bae Co.” )
The reported period covers work activities done in four issues:

1. A development of technical documentation to piston gap - sealing wear check stand.
2. A development of technical documentation to test stand and methodology of accelerated life-
time tests for Stirling-type cryocoolers against blockage of cryocooler displacer unit by cryogenic
deposits.
3. A development of technical documentation to stand and to mock-up test for compressor body
gas tightness at accelerated thermo- cycling
4. A development of technical documentation to compressor linear drive high-frequency stand
and to mock-up test of the flexible springs pilot samples at different frequencies.

In compliance with Issue 1, a first edition of principal pneumo- hydraulic scheme of the
test stand has been forwarded to the Customer Current report represents 2nd revised version of
above scheme (see Fig.2.1). Compressor gap- sealing wear check stand is an individual
component of the Helium Complex Stand (HCS) facility. Another constituent component of HCS
is a stand for accelerated tests to blockage of the displacer by condensed cryogenic deposits.
Such a designer’s concept has enabled us to sufficiently, almost as twice, reduce metal
consumption and cost of the HCS as a whole, and to arrange for more compact layout of HCS
equipment and facilities, thus saving a portion of HCS premise room.

In compliance with issue 2, there has been developed a methodology for accelerated
tests of the displacer blockage by condensed cryogenic deposit as represented in Chapter 1.
Besides this, there has been carried out a detailed design development of connections to
interface the HCS facilities with standard test equipment to be supplied by US-party. Chapter 2
represents a list of requirements to said test equipment. Here in this chapter are also
represented detailed connection schemes to interface the HCS with standard US-made test
equipment,including:

- a standard frequency test cryocooler;
- a high- frequency test cryocooler;
- two thermal chambers to stabilize temperature of cryocoolers
- cryocooler interface armature;
- two vacuum outpumping systems;
- facilities for filling the HCS with liquid nitrogen, admixture gases and distilled water;
- a mass spectrometer for gasouus media monitoring, and
- pressurized gas bottles.

These documental materials are assumed to enable the US- party to be prepared, in
advance, to discussion of technical aspects during pre-planned visit of SR&DB experts to the
AFRL in early February 2000.

Following the Issue 3 , there has been accomplished a development of the stand principal
4
schemes. In the course of development, there has appeared a necessity to experimentally
specify temperature regimes of thermocycling with purpose of selection for optimal cryoagent
and method of cooling hereof. For this reason, there has been - engineered a mock-up stand,
and tested under different temperature regimes a full- scale cryocooler body mock-up. Based
on test results, there has been determined cooling temperature of –70оС. Chapter 3.1
represents test results and resume hereto.
Chapter 3.2 represents technical requirements to three cooling system versions, with
application of:
- a standard cooling machine to be supplied by US-party;
- liquid nitrogen;
- solidified carbonic acid gas.
A final choice of cooling system requires a discussion with US-party at the would-be
meeting in AFRL.
In compliance with issue 4, there has been tested a compressor piston suspension mock-
up prototype with employment of a mock- up stand provided for these reasons in previous times.
As test results, there has been obtained a curve characteristic of the drive power dependence
on frequency within 30 до 1100 Hz range.
It was found that said curve possesses a series of specifically notable resonance peaks
of low power consumption rate, which is assumed to be a result of mechanical resonance that
occurs within springs as a whole and within separate structural parts of springs. In the course of
high- frequency test of compressor, there appears a need to determine said frequencies and,
hence, to rearrange the test procedures to a reduced or increased frequency. With this purpose,
the high- frequency compressor test stand will be provided with appropriate facilities. Chapter
3.3. covers detailed results data hereof.
Chapter 4 of the Report contains requirements to complete- set equipment and facilities
of US make for compressor body accelerated thermocycling test stand.
Chapter 5 of the Report includes similar requirements to compressor linear drive high-
frequency fatigue test stand.
5
1. ACCELERATED TESTS METHODOLOGY FOR STIRLING-TYPE CRYOCOOLERS
AGAINST CRYO-DEPOSIT FAILURES

Selected list of abbreviations:

A5 = helium mixture container unit
A6 = pollutant cryodeposit collector unit
A7 = vapor generator unit
CAU = cryodeposit accumulation unit, the «CAU-trap»
CH1 = cryocooler
CS1 = cryocooler
GC1... GC8 = eight gas bottles
HCS = helium complex stand facility.
LN = liquid nitrogen
MS = mass spectrometer
RS1 = vapor generator vessel
RS2 & RS3 = receiver vessels
TC1 = thermo-controlling chamber
UN2 = pipe ends
VH1 = inlet lock valve
VH2 = by-pass lock valve
VH3 = outlet lock valve
VF2 = adjustment valve

The accelerated tests for stability of Stirling-type cryocoolers against blockage of
cryogenic equipment by cryo-deposits is implemented by means of helium complex stand
(HCS) facility.
Principal pneumo-hydraulic scheme of the stand is represented at Fig 2.1.
These tests are available for both:
CS1-type cryocooler to operate at standard frequency, and
CH1-type cryocooler having undergone a cycle of high- frequency tests.
The HCS equipment and facilities for cryo-blockage accelerated tests provide solution of
the following tasks:
- long-term performance of the CS1 cryocooler at nominal frequency at maximum
admittable environmental temperature;
- change in composition and in amount of admixtures (being resultant outgassing
products of system-structure materials) in working fluid of the CS1 cryocooler, after its long-
term non-stop performance at nominal frequency and at maximum admittable environmental
temperature within 3 to 6 months interval;
- preparation and filling of CS1 and CH1 cryocoolers with water vapor of pre-determined
parameters;
- preparation and filling of CS1 and CH1 cryocoolers with working fluid containing pre-
determined amount of (CO , CO, N , CH etc) «pollutant» gas admixtures capable of
2 2 4
forming cryodeposit blocks inside the displacer unit structure;
- monitoring of admixture amounts and composition in working fluid of CS1 and CH1
cryocoolers at different regimes;
- implementing test procedures for CS1 and CH1 cryocoolers operating with «dirty»
working fluid to check out for compliance with parameters hereof (like cryostatting
temperature, consumed power, vibration level etc) to Certification-guaranteed data.
6

For performance test of the CS1 cryocooler, there will be employed US-made standard
facilities.

INTEGRATED TEST METHODOLOGY
1. Forecasting an Amount of Cryodeposits inside Cryocoolers in 10 years operation
Forecast procedures to predict an amount of cryodeposit «dirt» to accumulate inside the
cryocoolers by the end of their expected performance life should be carried out over 2 stages.
The first stage, one year long, includes 4 measurement procedures for amount of cryogenic dirt
accumulated, in every three months of operation within a cryocooler- displacer’s cold zone, due
to outgassing by cryocooler-component materials. At second stage, obtained results will be
analyzed, and following a special methodology, there should be carried out computations for
cryogenic «dirt» amount that would accumulate inside the cryocoolers by the end of their 10-
year service life.
Changes in composition and in amount of admixtures in working fluid of the
cryocooler that operated at nominal frequency should be measured in the following
manner:
1.1. The cryocooler should be stopped in order to re-warm its displacer unit up to room
temperature.
1.2. The cryocooler should be warmed up to 85oC ultimately permitted so-called «survival»
temperature being monitored by sensor of thermo-controlling chamber TC1 (of A3 unit)
and located near to the cryocooler mounting spot.
1.3. There is provided an extraction of helium samples from cryocooler, via heated thermo-
insulated piping, with purpose of admixture-amount control by means of mass-
spectrometer.
1.4. Further, helium is released from the cryocooler and passes through «trap», i.e.,
nitrogen cryodeposit accumulation unit (CAU) inside A6 unit out into environment at
0.11 Mpa residual pressure.
In the course of helium release and prior to finish, some portion of post-trap helium is
sampled with purpose of monitoring residual amount of admixtures by means of mass-
spectrometer.
1.5. Next, the cryocooler should be filled again with purified helium up to 1.4 MPa nominal
filling pressure, and retained under +85oC survival temperature for minimum 1 to 2
hours (the time term should be specified with methodology optimization with application
of cryocooler simulation unit).
1.6. The cryocooler shall be kept until its temperature goes down to +40oC (owing to
temperature decrease around cryocooler mounting spots inside the thermo-control
chamber down to 0-20oC).
1.7. The cryocooler shall be actuated on for 10 to 15 minutes in order to make the helium
mass agitated, and then be re-warmed up to +85oC again.
1.8. There is provided an extraction of helium samples from cryocooler, via heated thermo-
insulated piping, with purpose of admixture-amount monitoring by means of mass-
spectrometer.
1.9. Helium is released, for the second time, from the cryocooler through the same nitrogen
cryo- adsorption «trap» (of A6 unit) into environment up to 0.11 MPa residual pressure.
7
In the course of helium release and prior to finish, some portion of post- trap helium is
sampled with purpose of monitoring residual amount of admixtures by means of mass-
spectrometer.
1.10. The cryocooler should be filled again with purified helium up to 1.4 MPa filling
pressure, and be retained under maximum admittable temperature within minimum 1 to
2 hours
1.11.The cryocooler temperature shall be let down to +40oC owing to temperature decrease
for its mounting spots inside the thermo-control chamber down to 0-20oC.
1.12. The cryocooler shall be switched on again for 10 to 15 minutes to agitate helium.
1.13. The cryocooler shall be re-warmed up to +85oC.
1.14. An extraction of helium samples from cryocooler, via heated thermo-insulated piping, is
provided to control an amount of admixtures by means of mass-spectrometer.
If there occurs a notable appearance of admixture content in a given sample (i.e., up to
1-5% over the same in initially sampled helium, per para. 1.3) for any de-sublimating
component, the procedures per paras. 1.9 ... 1.14 should be reproduced again
If content of admixtures is negligible, tests should go further on per. para 1.15 and so
forth.
1.15. Helium should be released from the cryocooler for the third time, through the same cryo-
adsorption trap, out into environment up to 0.11 MPa residual pressure.
And again, another helium sample (prior to its release end) is routinely controlled by
means of mass spectrometer.
1.16. The cryogenic CAU-trap should be shut off the cryocooler system (by means of lock
valves). Now, the cryocooler should be used in tests for scavenging the compressor
piston-bore gap sealing.
1.17. Helium will be outpumped from the cold trap by means of membrane-type fore-vacuum
pump unit-1 up to maximum 1 Pa residual pressure.
1.18. The VH11 valve of CAU- trap in A6 unit should be shut up, thus separating cavities of
regenerating heat exchanger HR1, in order to freeze out the water from cryo-adsorber
AC1.
1.19. The interlocked CAU- trap should be warmed up to 100 ... 150oC temperature.
1.20. Temperature and pressure inside the CAU-trap cavities of determined volume should be
measured.
1.21. Contents of gases and vapors inside both cavities of the CAU-trap should be analyzed
by means of mass spectrometer, along with subsequent definition of percentage of
admixture-contents capable of forming cryodeposit blocks at cryocooler operation
temperatures.
1.22. Absolute value of cryodeposit amount accumulated within 3 months of the cryocooler
performance, inside its working fluid, should be computed.

2. Filling the CS1 or CH1 Cryocoolers with a Pre- Determined Amount of Water Vapors

Filling the cryocoolers with a pre- determined water vapors amount should be done my
means of vapor generator, the A7 unit.
2.1. The cryocooler should be vacuumized (usually by means of a membrane- type fore-
vacuum pump alone or, when necessary, together with a turbo- molecular pump of
outpumpung unit-1), and then cooled down to -40...-20oC by means of a relevant
thermo- controlling chamber.
8
2.2. At + 50 oC temperature,there should be arranged an equilibrium state inside the RS1
vapor generator vessel (with boiling degassed double- stillage distilled water), by means
of HC1 thermal chamber of A7 unit, and RS1 vapor generator.
2.3. Saturated water vapor from the A7 - RS1 vapor generator unit should be conveyed,
under equilibrium 92.5 mm Hg pressure and via VF1 adjustment valve, into
preliminarily outpumped receivers RS2 and RS3 possessing somewhat higher
temperature, like +65...+70oC. Further on, said receivers, RS2 and RS3, will be shut
off the RS1 vessel by means of valves VF1 and VH1.
2.4. Temperature of RS2 and RS3 vessels, of connecting piping hereof and gas- lock
armature is maintained as constant at +65...+70oC temperature level by means of A7-
HC1 thermo-chambers and helium complex stand facilities, along with auxiliary heaters
and temperature sensors upon locking valves of cryocoolers.
NOTE: these facilities are not shown in Fig.2.1
2.5. There is arranged an optimized volume of receivers, (of combination of RS2 + RS3, or
RS2 alone), along with computation for finite pressure of overheated steam herein, in
dependence on amount of water vapor required for filling a cryocooler.
2.6. Overheated steam is forwarded from vapor generator to a relevant «cold» cryocooler to
be frozen out.
2.7. Amount of water vapor filled into a cryocooler should be monitored through pressure
drop across vapor generator receivers RS2 and RS3.
3. Preparation and Filling the CS1 or CH1Cryocoolers with Working Fluid Containing a
Pre- Determined Amount of Gaseous Admixture Pollutants
3.1. A computed «dirty» working fluid of a cryocooler should be prepared in a preliminarily
cleaned (by means of vacuumizing with subsequent overheat) filling vessel RS1 of
helium mixture container unit A5 being outpumped down to maximum pressure 1 Pa by
means of membrane- type fore- vacuum pump of outpumping unit 1.
3.2. In order to provide required computed partial pressure values, the admixture pollutant
gases should be fed, one by one and at definite 20-35 oC temperature, from any of
eight bottles GC1... GC8 into a filling vessel, through adustment in-leaker*** valves and
a heat exchanger.
Pressure inside the filling vessel should be controlled by meams of vacuum and
vacuum-presser gauge sensors.
***NOTE: the «in-leaker» means a piezo-sensitive device that monitors microscopic
dosages of in- leaking gases for purpose of investigation
3.3. The filling vessel should be filled with helium from helium bottles GC1 and GC2 belonging
the stand facilities, whereby helium is purified inside the CAU- trap of A1 unit up to
computed pressure about 2.0 mPa.
3.4. Pollutant admixture content inside the prepared working fluid of cryocoolers should be
additionally monitored by means of mass spectrometer.
3.5. The «dirty» helium is fed from filling vessel (through VF2 adjustment valve)
simultaneously into both compressor and displacer cavities of the cryocooler, until
required filling pressure sets in.
3.6. The cryocooler should be pressurized by means of its own gas-locking armature.

4. Testing of the Cryocoolers Operating with «Dirty» Working Fluid
9
Testing of the cryocoolers that operate with «dirty» working fluid should be
implemented in compliance with standard methodology based on a «performance test» with
application of standard USA test equipment and facilities.
Check out for compliance of major cryocoolers characteristics (like cooling
temperature, consumed power, vibration level etc) to Certification-guaranteed data should
be carried out.